Gene regulation and protein synthesis

What are the 5 steps of transcription

RNA polymerase binding

DNA chain separation

Initiation

Elongation

Termination

What does TBP stand for?

TATA box binding protein

What is TFIID

A general transcription factor

What DNA region does RNA polymerase binding to during initiation?

The promoted

What begins pre-initiation complex assembly?

TATA-binding protein (TFIID) binding to TATA box

How does RNA polymerase get recruited?

General transcription factors assemble and bring in RNA polymerase to form the pre-initiation complex

What happens during transcription elongation?

RNA polymerase adds complementary ribonucleotides as it moves 3’ to 5’ along the DNA

What type of nucleotides are used in RNA synthesis?

Ribonucleotides with ribose sugar and uracil instead of thymine

What triggers transcription termination?

RNA polymerase reaches a termination signal in the DNA

What structure forms in the RNA that helps end transcription?

A stem-loop (hairpin) structure

How does the stem-loop cause termination?

It destabilises RNA polymerase, causing it to release the RNA and detach from the DNA

What are the two main domains of a specific transcription factor

A DNA-binding domain and a transcriptional activation domain

What do specific transcription factors bind to?

Specific DNA sequences near a promoter

How do enhancers influence transcription?

DNA looping brings enhancers close to the promoter, allowing factories to boost or repress transcription

Where can translation occur?

Cytoplasm but occasionally mitochondria

What is a codon?

A three-nucleotide sequence in mRNA that specifies an amino acid

Why is the genetic code considered redundant?

Multiple codons can code for the same amino acid

What is a silent mutation?

A nucleotide change that doesn’t alter the amino acid

What does it mean that the genetic code is degenerate?

Many amino acids are specified by more than one codon

What does it mean when genetic code is unambiguous?

Each codon corresponds to only one amino acid

What is reading frame?

One of three possible ways an mRNA sequence can be read in codons

What are the three letter of the start codon?

AUG

What molecule brings the correct amino acid to the ribosome during translation

TRNA

What enzyme attaches an amino acid to its corresponding tRNA

Aminoacyl-tRNA synthetase

What is the function of the anticodon during translation?

It ensures the tRNA binds the correct codon so the correct amino acid is added

Which tRNA start translation and what does it carry?

UAC carrying methionine

What completes the initiation complex and what energy is used

The large ribosomal subunit joins (using GTP), positioning the initiator tRNA in the P site

What delivers Aminoacetyl-tRNAs to the ribosome

EF-1alpha

What enzyme forms the peptide bond during elongation?

Peptidyl transferase

What is the role of EF-2 in elongation?

It shifts the ribosome along the mRNA by one codon

What are the three stop codon?

UAA, UAG, UGA

What happens after the release factor binds?

GTP is hydrolysed

What is a polysome?

A complex formed by multiple ribosomes

What determines where a protein goes in the cell?

Specific amino acid targeting sequences within the protein

What is protein modification?

Adding extra chemical groups to a protein to adjust its function

Why does protein degradation occur?

To remove unwanted or damaged proteins

What does ubiquitination do?

Targets proteins for degradation

What does cleavage do?

Activates or converts proteins